An insight into the mechanistic role of the common carotid artery on the hemodynamics at the carotid bifurcation.

Abstract

The rationale for this study lies in the well-known predilection for vascular disease of the carotid bifurcation, attributed to an altered shear stress distribution at the luminal surface and mitigated by helical fluid structures establishing inside the bifurcation. Here we investigate the mechanistic role played by the common carotid artery (CCA) in promoting complex intravascular flow and in influencing the hemodynamics at the distal carotid bifurcation. Fifty-five image-based computational hemodynamic models of eleven right carotid geometries were reconstructed from its brachiocephalic origin to above the bifurcation to assess how five different CCA reconstruction length affects intravascular fluid structures entering the bifurcation. A quantitative description of helical flow is adopted, in parallel to the description of disturbed shear at the bifurcation luminal surface. Our findings support the hypothesis that helical flow in CCA might reduce the likelihood of flow disturbances at the bifurcation. This confirms the physiological role of CCA in transporting and enforcing helical flow structures into the bifurcation, giving further contribution to the helicity-driven suppression of disturbed shear. A quantitative analysis of CCA geometry highlights the beneficial effect of proximal CCA curvature on helical flow and shows the complex interlacement among CCA geometry, helical flow, and disturbed shear at the bifurcation. Since helicity-based descriptors and geometric descriptors relative to the bifurcation have been shown to be significant predictors of disturbed shear, in principle they may be augmented by factors related to CCA geometry and hemodynamics.